Investigation of surface homogeneity of (3200) Phaethon

TL;DR

This study used time-series photometry and spectrometry to analyze asteroid (3200) Phaethon's surface, revealing a homogeneous southern hemisphere with no evidence of color variation or latitudinal differences, likely due to uniform thermal metamorphism.

Contribution

It provides new observational evidence that Phaethon's surface is homogeneous across latitudes, supported by spectral analysis and thermal modeling.

Findings

Southern hemisphere of Phaethon is homogeneous.

No detectable rotational color variation.

Uniform thermal metamorphism likely causes surface homogeneity.

Abstract

Time-series multi-band photometry and spectrometry were performed in Nov.-Dec. 2017 to investigate the homogeneity of the surface of asteroid (3200) Phaethon. We found that Phaethon is a B-type asteroid, in agreement with previous studies, and that it shows no evidence for rotational color variation. The sub-solar latitude during our observation period was approximately 55 degree S, which corresponded to the southern hemisphere of Phaethon. Thus, we found that the southern hemisphere of Phaethon has a homogeneous surface. We compared our spectra with existing spectral data to examine the latitudinal surface properties of Phaethon. The result showed that it doesn't have a latitudinal color variation. To explain this observation, we investigated the solar-radiation heating effect on Phaethon, and the result suggested that Phaethon underwent a uniform thermal metamorphism regardless of latitude, which was consistent with our observations. Based on this result, we discuss the homogeneity of the surface of Phaethon.